grasas y aceites,
64 (5), 572-582, 2013,
octubre-diciembre, issn: doi:
0017-3495 10.3989/gya.063013
Responses of fruit physiology and virgin oil quality to cold storage of mechanically harvested ‘Arbequina’ olives cultivated in hedgerow By K. Yousfi1, C.M. Weiland1 and J.M. García2, * 1
Department of Agroforestry Sciences, College of Engineering, University of Huelva. Campus Universitario de La Rábida, Carretera de Palos de La Frontera, s/n, 21819 Huelva, Spain 2 Department of Physiology and Technology of Plant Products. Instituto de la Grasa (CSIC). Avda. Padre García Tejero 4, 41012 Seville, Spain * Corresponding author:
[email protected]
RESUMEN Respuestas de la fisiología del fruto y de la calidad del aceite virgen al almacenamiento en frío de aceitunas ‘Arbequina’ de seto cosechadas mecánicamente El aumento de la producción de aceituna (Olea europaea L. cv. ‘Arbequina’), debido al uso creciente del cultivo superintensivo y la necesidad de un rápido procesamiento del fruto forzará a la industria a hacer una considerable inversión en maquinaria para el procesado, para mantener el nivel de calidad del aceite de oliva virgen (AOV). Este trabajo pretende estudiar cómo la temperatura de almacenamiento afecta a la fisiología de la aceituna y a la calidad del aceite, en orden de usar la conservación del fruto como una alternativa más barata y versátil al aumento de la capacidad de procesamiento. La aceituna ‘Arbequina’ no presentó síntomas de daños por frío durante 15 días de frigoconservación. La podredumbre, el desverdizado, el ablandamiento, la respiración y la producción de etileno de la aceituna aumentaron en relación directa a como aumentaba la temperatura de conservación. Estos hechos determinaron un deterioro proporcional de la acidez libre y de la calidad sensorial de los AOVs. Además, los contenidos de tocoferoles y de los principales grupos de compuestos fenólicos en los AOVs experimentaron una reducción durante la conservación del fruto en razón directa a la temperatura de almacenamiento utilizada. La frigoconservación a 2 °C preservó la integridad del fruto para mantener el nivel «Extra» de calidad durante un periodo de 12 días. PALABRAS CLAVE: Ablandamiento del fruto – Color del fruto – Compuestos fenólicos – Etileno – Olea europea – Poscosecha de aceituna – Respiración – Tocoferoles. SUMMARY Responses of fruit physiology and virgin oil quality to cold storage of mechanically harvested ‘Arbequina’ olives cultivated in hedgerow The increase in olive fruit production (Olea europaea L. cv. ‘Arbequina’), due to the increasing use of super-intensive cultivation and the need for a rapid fruit processing will force the industry to make a considerable investment in machinery for processing in order to maintain the level of quality of virgin olive oil (VOO). This work aims to study how the storage temperature affects the physiology of the olive and the quality of the oil, in order to use fruit storage as a cheaper and more versatile alternative to the increase in processing capacity. ‘Arbequina’ fruit did not present symptoms of chilling injury during 15 days of cold-storage. Postharvest
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decay, de-greening, softening, respiration and ethylene production of the olive fruit increased in direct relationship as the storage temperature increased. These facts determined a proportional deterioration of the free acidity and the sensory quality of the VOOs. Furthermore, the contents of tocopherols and of the main phenolic compounds in the VOO exhibited a reduction during fruit storage according to the increase in the temperature used. Storage at 2 °C preserved the integrity of the olive to maintain the best “Extra” level of VOO quality for a period of 12 days. KEY-WORDS: Ethylene – Fruit color – Fruit softening – Olea europaea – Olive postharvest – Phenolic compounds – Respiration – Tocopherols.
1. INTRODUCTION Over the last decade, super-intensive cultivation of the olive tree (>1000 trees/ha) is becoming increasingly important as it facilitates mechanized harvesting, leads to greater yields and reduces the effect of the typical olive tree alternation of production (Pastor-Vega et al., 2005; Gómez del Campo et al., 2009). Among the Spanish olive varieties used for the production of Virgin olive oil (VOO), only the cultivar ‘Arbequina’ is conveniently adapted to this type of cultivation. Factors such as its relatively small size, its precocity in the production of fruit, its high virgin oil yield and the excellent quality of its virgin oil have determined its almost exclusive use in this type of cultivation (Tous and Romero, 1992; Ferguson, 2006). However, the predictable increase in production by the use of this cultivation will pose a serious challenge for the olive industry, which will be struggling to process this quantity of fruit quickly enough before it deteriorates and, accordingly, before the quality of its oil is altered (García and Yousfi, 2006). In addition, the period in which the olive ‘Arbequina’ produces optimum quality VOO is relatively short (15-20 days). As its degree of maturation increases, the oil from this cultivar loses intensity in the sensory attributes that make it appealing to the consumer. Its initial golden-green color becomes transparent, its flavor becomes tasteless and its characteristic green almond smell fades as the skin of the fruit
RESPONSES OF FRUIT PHYSIOLOGY AND VIRGIN OIL QUALITY TO COLD STORAGE OF MECHANICALLY...
darkens (Morello et al., 2004). Therefore, to achieve a relevant level of VOO quality, total fruit production must be processed in a reduced period, which would involve the olive industry increasing its processing capacity, since super-intensive cultivation could multiply the production four-fold relative to the traditional cultivation of this tree (
